He is joining Newstalk ZB, replacing the retiring Justin du Fresne as Wellington talkback host.
The radio station confirmed that Plunket would begin his new role in January.
He also has a new job presenting TV3's weekend political show The Nation as well as writing a column for monthly Metro magazine.
"It has been an amazing 13 years and lasted longer than I expected it would," he said on air this morning.
"I would hope that notwithstanding some massive development in the field of genetics, I will be the longest ever serving co-host with you on Morning Report," he told long-serving colleague Geoff Robinson.
Plunket has won numerous media awards for his work.
He has not always had a smooth relationship with his employer and took Radio New Zealand to the Employment Relations Authority last year after he was banned from writing a political column in Metro.
RNZ argued that Plunket had a conflict of interest.
RNZ chief executive Peter Cavanagh said a political column could lessen Plunket's perceived objectivity as a Morning Report host.
The authority agreed that RNZ had the right to decide if Plunket's activities could be deemed an "actual or potential" conflict of interest.
But RNZ relented, allowing him to write the column.
Plunket has previously worked in television, including stints on Fair Go, a number of years as a TV3 political correspondent in the press gallery and with current affairs show Holmes.
